Problems compiling from source due to nlohmann_json linking about xeus HOT 5 CLOSED

In modern cmake, target_link_libraries is also used for header-only libraries. If it cannot find it, it will assume that you are trying to link with a runtime called nlohmann_json whichbis whatbis happening here.

nlohmann_json and other dependencies should be installed with cmake in the same prefix (-D CMAKE_INSTALL_PREFIX).

Is this how you installed nlohmann_json?

from xeus.

I install nlohmann_json as follows, without specifying a prefix, as I did with the other dependencies:

git clone https://github.com/nlohmann/json && \
    cd json && \
    cmake . && \
    make && \
    make install

This installs into /usr/local:

-- Installing: /usr/local/include/nlohmann
-- Installing: /usr/local/include/nlohmann/json.hpp
-- Installing: /usr/local/lib/cmake/nlohmann_json/nlohmann_jsonConfig.cmake
-- Installing: /usr/local/lib/cmake/nlohmann_json/nlohmann_jsonConfigVersion.cmake
-- Installing: /usr/local/lib/cmake/nlohmann_json/nlohmann_jsonTargets.cmake

from xeus.

Ok, then /usr/local is your prefix!
(This should work with master, but we generally recommend to not use the tip of master for any software, but at least the latest released tag).

When building xeus, could you do

cmake -D CMAKE_INSTALL_PREFIX=/usr/local and report the outcome?

from xeus.

I get the same:

/usr/bin/x86_64-linux-gnu-ld: cannot find -lnlohmann_json
collect2: error: ld returned 1 exit status
CMakeFiles/xeus.dir/build.make:435: recipe for target 'libxeus.so.1.0.1' failed
make[2]: *** [libxeus.so.1.0.1] Error 1
make[1]: *** [CMakeFiles/xeus.dir/all] Error 2
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/xeus.dir/all' failed
Makefile:129: recipe for target 'all' failed

You can see the full list within a Dockerfile I'm working on:

https://github.com/sdwfrost/polyglot-playground/blob/master/Dockerfile

from xeus.

@sdwfrost I figured it out. The latest release of nlohmann_json made a backward incompatible change by adding a namespace to its cmake target names.

Cf. issue nlohmann/json#1243 and commit nlohmann/json@33a2154.

I am updating xeus to use the latest nlohmann_json and these target names.

from xeus.